HSP90a plays an important role in regulating enzymes important for metabolic functions such as eNOS and LKB1. Therefore, it is possible that HSP90a plays a broader role in the regulation of energy metabolism in whole animals. We analyzed how HSP90 changes with aging in skeletal muscle and fat in animals. We find that expression and activity of HSP90a decreases with aging in primates and in rodents. HSP90a is also important for the activity of a number of enzymes that are important for energy metabolism and metabolic rate.